Abstract P104: Serum 25-hydroxyvitamin D Levels and Incidence of Atrial Fibrillation: The Atherosclerosis Risk in Communities Study

Introduction: Low levels of serum 25-hydroxyvitamin D [25(OH)D] have been associated with an increased risk of cardiovascular disease (CVD). However, few studies have examined the association of 25(OH)D with atrial fibrillation (AF). Hypotheses: Individuals with clinically deficient serum 25(OH)D levels (<20 ng/mL) will have an increased risk for AF, and the association will be stronger among whites than blacks. Methods: The Atherosclerosis Risk in Communities (ARIC) study is a biracial, community-based cohort in the United States. A total of 12,300 ARIC participants (77% white, 57% women, mean age 57) with available 25(OH)D levels, and who were free of AF at baseline (1990-92), were followed through 2011. Total serum 25(OH)D was measured in stored samples at baseline using LCMS and adjusted for month of blood draw to account for seasonal differences in 25(OH)D levels. Incident AF cases were identified from electrocardiograms, hospital discharge codes, and death certificates. Multivariable Cox models were used to estimate hazard ratios and 95% confidence intervals for AF associated with serum 25(OH)D levels by clinical cut-points. Interactions by age, race, and sex were tested. Results: During a median follow-up of 20 years, there were 1,706 incident AF events. Those with deficient 25(OH)D levels ( 30 ng/mL) after adjustment for demographics (Table, model 1). Additional adjustment for cardiovascular risk factors and history of CVD attenuated the associations (Table, models 2 and 3). A significant interaction with age (p=0.01), but not with race or sex (p >0.40), was identified, with an inverse association between serum 25(OH)D in younger but not older individuals (Table). Conclusions: After accounting for traditional cardiovascular risk factors, low serum 25(OH)D was not associated with risk of incident AF in this community-based population. However, an apparent association in younger individuals (47-57) warrants further investigation. ![][1] [1]: /embed/graphic-1.gif